This invention relates to an effect control in an electronic musical instrument capable of producing musical tones imparted with desired effects such as ensemble, reverberation, chorus, pitch change and delay and, more particularly, to an effect control in such electronic musical instrument capable of switching generation of a tone imparted with an effect and a normal tone.
Known in the art is an electronic musical instruments capable of imparting various effects as described above to musical tones to provide a variety to produced tones. In such electronic musical instrument, there is provided an effect selection switch for imparting a selected effect whereby a tone imparted with an effect and a normal tone which is not imparted with any effect are selectively generated by operation of this effect selection switch.
In the prior art electronic musical instrument, however, when this effect selection switch is turned on, a selected effect is imparted to a tone simultaneously with turning on of the switch. An abrupt change therefore occurs by this switch operation in a tone which has been sounded since before turning on of the switch with a result that the tone tends to become an unnatural tone. There is, for example, a processing for obtaining an ensemble effect according to which tones are produced in two or more lines and timing of panning in each of these lines is made different. When the effect selection switch is turned on during generation of tones in this case, a noise is generated due to the abrupt change in the panning.
In a case where the effect selection switch is operated during performance, for example when the performer who is performing the electronic musical instrument while watching a score wishes to impart an effect from the beginning of next bar in the score, the timing at which the switch is turned on must be coincidental with the beginning of the bar in the prior art musical instrument. In most cases, an operation for depressing a new key is necessary at the same timing as this timing and, therefore, the performer must perform two operations simultaneously. This requires a considerable skill which is too difficult for a beginner and is fairly troublesome even for a skilled performer with resulting difficulty in performance.
For producing an ensemble effect, for example, there is a processing called "key-on delay" applied to tones generated in two lines. This processing must be performed during key-on and, accordingly, it is not possible to adopt this processing in the prior art electronic musical instrument in which the ensemble effect is imparted simultaneously with turning on of an ensemble switch.